The present invention relates to the art of shaving, and, in particular, to improving the ease with which a shaving cartridge can be drawn across the skin during shaving.
In wet-shaving razor systems, there are several factors which can contribute to discomfort during shaving. Such factors include frictional drag of the razor across the skin, the force needed to sever the hair which, in turn, depends on, among other things, the mechanical strength of the hair protein structure, and clogging of the razor parts with whisker and skin debris. Other detracting factors relate to skin conditions such as rashes, eruptions, and previously-inflicted nicks and cuts.
Efforts to remedy at least some of the above problems have included the use of pre-shave and after-shave lotions, special whisker-softening lathers or agents, blood coagulants and other medicinal or soothing bio-effecting agents.
Even though shaving comfort can, to some degree, be enhanced by use of one or more of the above-mentioned aids, the requirement that they be applied before, during, or after shaving (because of loss due to evaporation or repeated shaving strokes) lessens the effectiveness of pre-applied aids and post-shaving applications.
In view of the problems listed above with regard to improving wet-shaving technique by addition of one or more agents, it is presently believed that a shavingenhancing agent integrally included with the shaving instrument would provide improved shaving features.
To that end, U.S. Pat. No. 4,170,821 to Booth discloses a solid water-soluble shaving aid incorporated in a disposable razor blade cartridge which gradually dissolves during the act of wet shaving. The shaving aid, in the form of a lubricant, whisker softener, razor cleanser, medicinal agent, cosmetic agent or combination thereof is embedded, dispersed into, formed as an integral component of, or otherwise affixed to the cartridge structure adjacent the shaving edge or edges of single or multiple blades supported therein. The shaving aid can be water-soluble lubricating oil such as microencapsulated silicone oil; water-soluble polyethylene oxide; non-ionic polyacrylamide; and/or a natural polysaccharide derived from plant materials, e.g., guar gum; a depilatory agent; a medicinal agent for killing bacteria or repairing skin condition; a cosmetic agent for softening the skin; or a blood coagulant. The Booth '821 disclosure describes a shaving aid which functions by being deposited on the skin in use through dissolution in water.
U.K. Patent Application G.B. No. 2 024 082 A of Pentney and Calvert discloses a shaving unit having at least one blade and a blade support of moulded polymeric material which provides a skin-engaging cap and guard surfaces. The guard surfaces are formed wholly or in part of a moulded mixture of at least one hydrophobic material and at least one water-leachable hydrophilic polymeric material such that during shaving the water present on the area to be shaved leaches out the hydrophilic material and, consequently, serves as a lubricant. Similar to the Booth '821 disclosure, the surface-affecting agent or component of Pentney and Calvert is deposited in use by dissolution in water. This feature present in both the above disclosures can result in several drawbacks relating to useful shaving unit life, unnecessary shelf-life problems and restrictions on use caused by sensitivity to moisture, possible agent-induced problems including concentration and rate of release, etc. These problems are exacerbated by the use of the lubricant in the presence of an abrasive such as whiskers on the skin which can cause excessive and accelerated deterioration. The lubricant can leave the shaver with a sticky feeling and can lead to itching and irritation. Additionally, lubricant deposited on the skin can reduce the important tensioning and conditioning effect of a guard thereby leading to lower quality shaves.
In U.S. Pat. No. 4,100,309 and U.S. Pat. No. 4,119,094, both to Micklus and Ou-Yang, coated articles are described, and a method for coating suitable substrates with a polyvinylpyrrolidone-polyurethane interpolymer. The coatings are obtained by a two-step procedure using first a solution of isocyanate containing prepolymer and polyurethane followed by a solution of polyvinylpyrollidone. The isocyanate can be modified with chain extenders (diols, etc.) which effectively produce a linear thermoplastic polyurethane in situ. This preparative route yields thin coatings on the order of about 0.0001 in. (2.5 .mu.m) which are not of uniform composition throughout (two separate layers intermixed at the interface) and are not suitable for the preparation of integral articles, films, foams or matrices with regular and uniform physical and mechanical properties. There is no indication, by Micklus and Ou-Yang to provide a coating lubricious when wet which must withstand abrasive forces while in the lubricious condition.
The prior art seeks primarily to alter shaving friction between skin and skin-engaging surface, by the action of requiring a lubricant to be deposited on the skin.
Thus, it is an object of the present invention to provide a shaving article having a reduced coefficient of friction in the presence of water which is reusable without loss through dissolution of the reduced friction feature.
It is another object of the invention to provide a coating readily applied to a shaving article which provides a reduced coefficient of friction in the presence of water even upon repeated use of the shaving article without loss through dissolution of the lubricating agent.
It is still another object of the invention to provide a lubricious coating to a surface of a shaving article which will substantially adhere to the surface after repeated use, and which will remain functional even after soaking in water for an extended period of time.
Yet another object of the invention is to provide a lubricious coating for a shaving article which can be used for articles made of diverse materials.
Another object of the present invention is to provide a coating for a shaving article which when wetted with water swells and conforms to the skin surface producing a cushioning effect during the act of shaving.
Other objects of the invention will become known to those skilled in the art in view of the present disclosure.